Cryosurgery is a well established surgical method which is useful in the treatment of many conditions and which involves the application of extreme cold to tissues to effect freezing of the tissues. The instruments used are, in general, of two types, the spray type wherein cold refrigerant is sprayed directly onto the tissue to be frozen, and the closed end cryotip type in which the refrigerant is delivered to a portion of the tip that is inserted into the tissue. In probe type instruments, as opposed to direct topical application of a cryogen, cryosurgery may include the introduction of a low boiling point refrigerant into the closed probe tip, gas expansion utilizing a Joule-Thompson effect, employing the latent heat of vaporization such as with freon, precooled gases and liquids, or thermoelectric cooling.
A preferred form of cryosurgery employs a closed end probe through which a low boiling point refrigerant or Joule-Thompson expansion fluid is circulated. Such a closed end probe confines the cryogenic fluid within the instrument rather than applying it directly to the tissues. In closed end probes, the cold generated by a cryogenic fluid is confined to the area of the probe tip where heat transfer occurs across the probe tip to the surrounding tissues to form an ice ball of frozen tissue.
Closed end probes are commonly used in systems wherein a remote source of cryogen or a refrigeration console is connected to the probe via a transfer hose. Examples of such probes and probe systems include U.S. Pat. No. 2,319,542, Hall, U.S. Pat. No. 3,272,203, Chato, U.S. Pat. No. 3,398,738 Lamb, et al., U.S. Pat. No. 3,425,419, Dato, U.S. Pat. No. 3,502,081, Amoils, U.S. Pat. No. 3,507,283, Thomas, Jr., U.S. Pat. No. 3,696,813 Wallach, U.S. Pat. No. 3,807,403, Stumpf, et al., U.S. Pat. No. 3,886,945, Stumpf, et al. U.S. Pat. No. 3,918,439 Zimmer, U.S. Pat. No. 4,211,231, Rzasa, U.S. Pat. No. 5,334,181, Rubinsky, et al., U.S. Pat. No. 5,520,682, Baust, et al., and U.S. Pat. No. 5,573,532, Chang, et al. These systems are necessarily bulky and not easily movable from one location to the other, nor are they well suited to use outside of a formal operating room or in minor surgical procedures due to their cost and maintenance requirements.
In contrast, open end, or spray type, tips are commonly used in less expensive and disposable hand held systems, generally for topical cryotreatments. Examples of these types of systems include U.S. Pat. No. 3,411,483, Canoy, U.S. Pat. No. 3,534,739 Bryne, U.S. Pat. No. 3,794,039, Kollner, et al., U.S. Pat. No. 3,823,718, Tromovitch, U.S. Pat. No. 3,901,241, Allen, Jr., U.S. Pat. No. 4,787,385, Pfistershammer, and U.S. Pat. No. 4,043,341, Tromovitch. Such devices are not suitable for use in procedures performed within the body due to the difficulty in controlling the amount of cryogen released and the effects of over spray on surrounding tissues.
Portable, hand held, closed end probe apparatus where a charge of cryogen is supplied from a reservoir are known. However, these devices tend to be limited in utility to small site applications such as in ophthalmic surgery. In many cases, the reservoir of cryogen is built into the device and is neither refillable nor replaceable necessitating that the entire apparatus be removed from the site and replaced if additional cooling is necessary when the cryogen runs out. Such devices are represented by U.S. Pat. No. 3,910,278, Crandell, et al., U.S. Pat. No. 3,951,152, Crandell, et al., U.S. Pat. No. 3,993,075 Lisenbee, et al., U.S. Pat. No. 3,524,446, Crump, et al., and U.S. Pat. No. 3,830,239, Stumpf, et al. In those cases where the reservoir within the tool is refillable, this requires the presence of a separate charging unit, as in U.S. Pat. No. 3,425,417, Kanabar, et al. and U.S. Pat. No. 3,434,477, Thomas, Jr. Devices which permit the replacement of cryogen reservoir have structures which require partial disassembly of the probe body in order to effect the removal of the empty reservoir and replacement with a fresh one or are of a size which renders such replacement difficult while the probe remains in place at the surgical site. Examples of these devices are shown in U.S. Pat. No. 2,746,264, Keyes, U.S. Pat. No. 3,259,131, Kanbar, et al., U.S. Pat. No. 3,343,544, Dunn, et al., U.S. Pat. No. 3,532,094, Stahl, U.S. Pat. No. 3,575,176, Crump, et al. and U.S. Pat. No. 3,933,156, Riggi.
Absent from the prior art is any suggestion of a portable, hand held, self-contained cryosurgical system having the capability of handling a plurality of cryogens either individually or simultaneously. Nor is there any suggestion of such a system which has the capability of being connected to and using cryogen from a remote source, such as a refrigerating console or an auxiliary tank, simultaneously with a changeable, self contained source of the same or a different cryogen and where the surgeon can readily switch from one cryogen to the other or use a mixture of the two. Furthermore, the prior art hand held systems are limited to use with one probe at a time probe, there being no provisions for mounting multiple probes to one device.
One patent, U.S. Pat. No. 4,376,376, Gregory discloses a cryogenic device operable in single or dual phase and with a range of nozzle sizes. This patent presents an open-nozzle spray type device in which a liquid cryogen stored in a hand held Dewar is supplied through an orifice into an expansion chamber on which a nozzle is mounted. A pressurized gas from a pressure regulated gas source is supplied to the device as a means to control gas pressure in the expansion chamber and the Dewar and to provide a single phase gas flow or a dual phase gas and liquid flow to the nozzle. The pressurized gas flow serves to maintain a stable flow of the liquid cryogen from the Dewar by combined manipulation of a venting passage and gas flow pinch valve. The pressurized gas also serves to pressurize the Dewar to ensure proper flow of liquid cryogen to the expansion chamber. Thus, although the Gregory device discloses selective single or dual phase flow of cryogen, it is not possible to achieve the dual phase absent the application of the pressurized gas and single phase flow. Furthermore, there is no provision for use of the apparatus with closed tip cryoprobes or with multiple probe systems.
Another drawback to the prior art portable, hand held cryosurgical devices occurs when the area to be treated is too large or irregularly shaped to be totally destroyed by only a single probe tip. It often happens that the size and shape of a tumor being treated is not fully recognized until after surgery begins. Also, it is not uncommon for a surgeon to find multiple tumors during surgery. With only a single cryosurgical instrument probe, the surgeon cannot always efficiently or safely treat large or multiple tumors. In the larger console type cryosurgical systems this problem has been solved by providing a manifold in the console which has a plurality of ports for connection of probe hoses such as in U.S. Pat. No. 2,319,542 and U.S. Pat. No. 5,334,181. However, no manifold system has been devised for use with portable hand held probes which have a self carried source of cryogen and, particularly, where the structure of the prior probe units are such that it is not possible to use a plurality of probes having self contained cryogen sources in close proximity with each other. Moreover, known hand held units are not designed to be capable of handling more than one probe at a time.